Device and method for the telecontrol of an object

ABSTRACT

A vehicle (V) is fitted with a primary receiver/emitter cell (1) containing a first code (C1) and a secondary receiver/emitter cell (2) containing a second code (C2) as well as a first representation (FR1) of the first code (C1). The two cells receive respectively primary (EIB1, EIA1) and secondary (EIB2) selective interrogations (OI) to which they respond by emitting respectively a primary response (ERB 1, ERA 1) representing the first code (C1) and a secondary response (ERB2) representing the second code (C2). Then the secondary cell (2) responds alone to a complementary interrogation (EIC) which contains a second representation (SR2) of the first and second codes emitted, together with an order.

BACKGROUND OF THE INVENTION

The invention relates to the telecontrol of objects, and especially thetelecontrol of the movement of automotive vehicles, for the purposes ofproducing an effective deterrent against theft and/or of allowing"transactions".

A transaction is understood to mean any type of collecting ordispatching of data with the aim of respectively receiving particularsoriginating from the interrogated object or of sending information tosaid object. This could involve, especially, checking the level of abattery, validating the toll for a car park or motorway, identifying anobject, replacing a code stored in a rewritable memory, controlling thetriggering of an alarm.

Various means are already known which are used as deterrent against thetheft of automobiles. One of them consists in remotely reading one ormore marks which are, carried by the vehicle and which are able toidentify it.

Such devices comprise an interrogator unit capable of effecting aprimary interrogation using waves so as selectively to interrogate atleast one primary receiver/transmitter cell housed in or on said objectand containing in primary storage means a first code, and of receivingfrom said primary cell a primary response able to represent a part atleast of this first code.

A device of this type is known especially through French Patent No. 8917133 (FR-A-2 656449), which describes a method for the control of themovement of objects, as well as the associated device. This devicecomprises at least one compulsory transitway equipped with a fixedtransmitter/receiver reader forming an interrogator unit, connected to astation and at least one receiver/transmitter cell housed in or on thevehicle

When a vehicle passes through the transitway above the interrogatorunit, this prompts the transmission of an identification code common toall the cells installed in the vehicle. This identification code isreceived by the cell, which then compares it with the identificationcode which it contains in a memory of electrically programmable type. Ifthe two codes are identical, the cell transmits toward the interrogatorunit a signal dependent on its own identification code which iscontained in a read only memory. The signal transmitted by the cell isthen received by the interrogator unit, which forwards it to processingmeans which deduce the identification code of the vehicle therefrom,which they are then going to compare with the codes of the equippedvehicles, which are contained in files.

Such a solution offers good protection against frauds of mechanical type(destruction or shielding of the cell) when the cell is installed in aninvisible manner in the vehicle.

However, this known solution does not make it possible to protectagainst certain electronic frauds since:

firstly, the identification codes individual to the cells cannot bemodified, given that they are contained in the read only memory of acell to which access is made difficult, or even impossible, through itsinstallation;

secondly, given that the code transmitted by the interrogator unit iscommon to all the cells and that the codes individual to each cell arecontained in a file, anybody having had access at a given instant tosaid file is in a position to make and install a replacement decoy on agiven vehicle;

thirdly, the interrogator unit can effect only a single interrogationconsisting in obtaining the code individual to each cell, thisprecluding any transaction other than that of identification.

Moreover, the interrogator unit being fixed, such a solution does notmake it possible to effect an identification just anywhere.

SUMMARY OF THE INVENTION

The present invention proposes a means of multiple transaction, andespecially of anti-theft deterrent suitable for remedying the aforesaiddrawbacks.

For this purpose it proposes a device of the type described earlier andfurthermore comprising at least one secondary receiver/transmitter cellhoused in or on said object and containing in secondary storage means asecond code and a first representation of a part at least of the firstcode, and capable of transmitting, in response to a secondaryinterrogation, a secondary response able to represent a part at least ofthis second code, as well as of effecting, after a primary interrogationof the primary cell and a secondary interrogation of the secondary cell,at least one complementary response in response to a complementaryinterrogation effected by the interrogator unit, said complementaryinterrogation containing a second representation of a part at least ofthe first and second codes transmitted respectively by said primary andsecondary cells in response to the primary and secondary interrogations.

This allows the secondary cell to effect a complementary responsedepending on the primary and secondary responses of the primary andsecondary cells, respectively.

Thus, the identification of a vehicle by an interrogator unitnecessarily involves the interrogation of two cells, one possiblyvisible and made in the form of a sticker affixed to the windscreen ofthe vehicle, the other being invisible on account of its installationinside said vehicle.

Additionally, such a device permits all sorts of remote transactionssince the number of transmissions/receptions between the interrogatorunit, which is not necessarily fixed, and one at least of the cells isnot limited to 1.

According to another characteristic of the invention, thetransmission/reception links between the interrogator unit and one atleast of the cells are effected on at least four distinct frequencies.This allows the interrogator unit to store selectively the part at leastof the first and second codes transmitted by the primary and secondarycells in response to the primary and secondary interrogations, dependingon the frequencies of transmission of the primary and secondaryresponses of the cells.

Thus, the interrogation of a cell is carried out independently of theother cells, thus avoiding conflicts of information and appreciablyrestricting the possibilities of jamming.

This effect is further strengthened through the fact that theinterrogations can be effected either electromagnetically, orinductively.

According to yet another characteristic of the invention, thecomplementary interrogation furthermore comprises a command area whichincludes a command to execute a "transaction". Moreover, in the event ofabsence of response of one at least of the primary and secondary cells,the second representation of the part at least of the absent code isreplaced with a specific code declaring absence of said absent cell.

Thereby, the secondary cell can be apprised in a single complementaryinterrogation, on the one hand, of the transaction requested and, on theother hand, of the presence or absence of the first cell.

According to yet another characteristic of the invention, the secondarycell furthermore comprises processing means capable of comparing thecodes of the primary and secondary cells, contained in these secondarystorage means, with the second representation of the parts at least ofthe respective codes of the primary and secondary cells included withinthe complementary interrogation.

Thus, in a particularly advantageous manner, it is no longer theinterrogator unit which effects verification of the codes of the cellsby comparison with codes contained in a file, as is known, but it is thesecondary cell which is housed in or on said object which hencefortheffects said comparison.

Advantageously, the primary and secondary storage means are rewritable.

Thus, an interrogator unit situated in proximity to an object equippedwith the cells according to the invention is also capable of modifyingon command the first code contained in the primary storage means and itsfirst representation in the secondary storage means, and/or the secondcode contained in the secondary storage means.

Consequently, the codes contained in each cell may be changed at anymoment, thus appreciably limiting the possibilities for electronicfraud.

The invention also describes a method for the telecontrol of an object,in which in a known manner:

a) the object is furnished with at least one primaryreceiver/transmitter cell housed in or on said object and containing inprimary storage means a first code, and capable of transmitting aprimary response in response to a primary interrogation, and

b) a primary selective interrogation using waves of this primary cell isundertaken, and a primary response able to represent a part at least ofthe first code is received from said primary cell.

The method according to the invention makes provision that:

in step a), there is provided at least one secondaryreceiver/transmitter cell housed in or on said object and containing insecondary storage means a second code and a first representation of apart at least of the first code, said secondary cell being capable oftransmitting a secondary response in response to a secondaryinterrogation effected by the interrogator unit, and at least onecomplementary response in response to a complementary interrogationeffected by said interrogator unit,

in step b) a secondary selective interrogation using waves of thesecondary cell is undertaken, and a secondary response able to representa part at least of the second code is received from said secondary cell,and

said method according to the invention furthermore includes:

a step c) in which there is transmitted to the secondary cell acomplementary interrogation containing a second representation of a partat least of the first and second codes transmitted by said primary andsecondary cells in step b),

a step d) in which the secondary cell compares the second code and thefirst representation of a part at least of the first code, which arecontained in its secondary storage means, with the second representationof the parts at least of the respective codes of the primary andsecondary cells which are included within the complementaryinterrogation, and

a step e) in which the secondary cell transmits at least a complementaryresponse as a function of the complementary interrogation received instep c).

According to another aspect of the method according to the invention, inthe event of at least partially unsuccessful comparison in step d),there is provision to recommence at least once steps b) to d), and toincrement an incrementation counter housed in the secondary cell.

Moreover, the number of permitted repetitions of steps b) to d), in theevent of at least partially unsuccessful comparison, is predetermined,thus triggering, in the event of the exceeding of said predeterminednumber, the transmission by the secondary spell of an alarm response.

Thus, in the event of malfunctioning or absence of one of the cells, andespecially of the primary cell, the interrogator unit is apprised onlyin the event of confirmation of non-success of steps b) to d), thusallowing it to alert either the possessor of the interrogator unit, ormore directly a central station having a link with said interrogatorunit.

Other characteristics and advantages of the invention will emerge onexamining the detailed description below, and the appended drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the links between the various elementsmaking up the device;

FIG. 2 is a basic diagram of a device implementing the invention;

FIG. 3 is a flowchart illustrating the main steps of the communicationprotocol according to the invention;

FIG. 4 is a basic diagram of a fixed device also implementing theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reference will first be made to FIGS. 1 and 2 in order to describe themain elements making up the device according to an embodiment of theinvention.

In this embodiment, the device comprises a primary cell 1 and asecondary cell 2 which are housed in a vehicle V, and an interrogatorunit OI suitable for remotely interrogating using waves the primary 1and secondary 2 cells.

The primary cell 1 is for example made in the form of a sticker which isattached to the windscreen of the vehicle V.

It comprises a reception module R1 and a transmission module E1 forcommunicating with the interrogator unit OI, a primary control moduleMC1 suitable for performing predetermined operations in response to aninterrogation of said interrogator unit OI, rewritable primary storagemeans M1 containing a first code C1 which is specific thereto, and acommunication module MD1 for communicating with the driver of thevehicle V.

The primary control module MC1 contains a low voltage battery driven bya timeout circuit permitting two states: a standby state which consumesno energy, and an operating state for responding to an interrogation.

This primary module MC1, is connected firstly to the receiver part R1 ofthe reception/transmission module from which it receives the data,secondly to the primary storage means M1, thus allowing it either toextract the first code C1 therefrom or to carry out on command thereplacement of said first code C1, thirdly to the transmitter part E1 ofthe reception/transmission module, thus allowing it to respond to aninterrogation or to transmit an alarm if need be, and fourthly to thecommunication module MD1 which it notifies of problems in the event, forexample, of poor reception during an interrogation of the primary cell1, or of poor operation of one of the elements making up the primarycell 1.

Such a communication between MD1 and the driver can be effected by usinga light-emitting diode or a buzzer.

The secondary cell 2 is for example made in the form of a packageinstalled in the structure of the vehicle V, this rendering it invisibleand hence protecting it from frauds of a mechanical type.

It comprises a reception module R2 and a transmission module E2 forcommunicating with the interrogator unit OI, a secondary control moduleMC2 suitable for performing predetermined operations in response to aninterrogation of said interrogator unit OI, a processing module MT2suitable for performing processings of data arising from the secondarycontrol module MC2 and for effecting one or more responses in order torespond to an interrogation, and rewritable secondary storage means M2containing in a first part M2-1 a first representation FR1 of a part atleast of the first code C1 and in a second part M2-2 a second code C2individual thereto.

The secondary control module MC1 contains a low voltage battery drivenby a timeout circuit permitting two states: a standby state whichconsumes no energy, and an operating state for responding to aninterrogation.

This secondary control module MC1 is connected firstly to the receiverpart R2 of the receiver/transmitter module from which it receives thedata, secondly to the secondary storage means M2, thus allowing it toperform therein the replacement on command of the second code C2 and/orof the first representation FR1 of the first code, and thirdly to theprocessing module MT2 to which it delivers commands and/or data arisingfrom the receiver R2.

The processing module MT2 is also connected on the one hand to thesecondary storage means M2, thus allowing it to extract therefrom thecodes which they contain, and on the other hand to the transmitter partE2 of the reception/transmission module, thus allowing it to respond tothe interrogations or to transmit an alarm if need be.

Each reception module of a cell R1 or R2 is made in such a way that itcan receive transmissions effected electromagnetically or inductively.

The interrogator unit OI comprises a first transmission module OIE1 andreception module OIR1 for communicating with the primary cell 1, asecond transmission module OIE2 and reception module OIR2 forcommunicating with the secondary cell 2, storage means OIM1 and OIM2suitable for storing data arising respectively from the receiver partsOIR1 and OIR2, a control module MCOI suitable for controlling on commandthe interrogation of the primary 1 and secondary 2 cells, as well as ofreceiving data arising from a processing module MTOI which processes thedata arising from the storage means OIM or from the receiver part OIR2of the second transmission/reception module.

Each transmission module OIE1 and OIE2 is suitable for interrogating acell electromagnetically or inductively.

The processing module MTOI is connected firstly to the receiver partOIR2 of the second transmission/reception module which provides it withthe data to be processed arising directly from the secondary cell 2,secondly to the storage means OIM1 and OIM2, thus allowing it to extracttherefrom the codes which they contain, thirdly to the control moduleMCOI, from which it receives predetermined commands permitting it tocarry out a processing of data, and fourthly to the transmitter part OI2of the second transmission/reception module in order to instructinterrogation of the secondary cell after certain processings.

The separation of the transmission/reception modules of the interrogatorunit OI allows each cell 1 or 2 to communicate with said interrogatorunit OI on frequencies which differ in transmission as in reception.

The primary cell 1 is capable of effecting a so-called "primary"response ERB1, ERA1 able to represent a part at least of the first codeC1 which it contains, in response to a so-called "primary" interrogationeffected by an interrogator unit OI. This code C1 will be able tocontain for example 16 bits.

The secondary cell 2 is capable of effecting a secondary response ERB2able to represent a part at least of the second code C2 which itcontains, as well as at least one so-called "complementary" response, inresponse to a so-called "complementary" interrogation effected by aninterrogator unit OI. This code C2 will be able to contain for example16 bits.

A complementary interrogation comprises a second representation SR2 of apart at least of the first and second codes transmitted by the primary 1and secondary 2 cells in response to the primary and secondaryinterrogations, as well as a command area containing a command toexecute a "transaction".

The interrogations between the interrogator unit OI and the primary 1and secondary 2 cells are effected for example at 125 kHz and 62.5 kHzrespectively, whereas the responses between the primary 1 and secondary2 cells and the interrogator unit OI are effected respectively, forexample, at 225 MHz and 30.875 MHz.

In this way, the responses of each cell are selected directly by thereceiver OIR whose frequency is centered on that of said response.

This particularly advantageous solution is certainly more cumbersome,but it has the advantage of rendering the links between cellsindependent, thus avoiding conflicts of information. Moreover, itenables the responses transmitted on different frequencies to be storedin different memories, without use of a filter, thus appreciablysimplifying the processing of the data.

In order to describe the telecontrol method according to the invention,reference is made to FIG. 3.

This method is divided into 5 steps:

a step a) in which the primary 1 and secondary 2 cells are set up in thevehicle V, the primary cell 1 containing a first specific code C1 in itsprimary memory M1, and the secondary cell 2 containing a second specificcode C2 as well as a first representation FR1 of the first code C1respectively in the second M2-2 and first M2-1 parts of its secondarymemory M2;

a step b) in which the primary selective interrogation EIB1, EIA1 of theprimary cell 1 is undertaken, followed by the secondary selectiveinterrogation EIB2 of the secondary cell 2. The primary and secondaryinterrogations may either be simultaneous or successive.

Each cell responds to the primary or secondary interrogation byreturning a primary or secondary response ERB1, ERA1 and ERB2 toward theinterrogator unit OI which stores the code contained in each response inone of the memories, OIM1 or OIM2 depending on the frequency of saidresponse;

a step c) in which the interrogator unit OI transmits to the secondarycell 2 a complementary interrogation OIC containing a secondrepresentation SR2 of a part at least of the first C1 and second C2codes transmitted by said primary 1 and secondary 2 cells in step b);

a step d) in which the secondary cell 2 compares, by virtue of itsprocessing module MT2, the second code C2 and the first representationFR1 which is contained in its secondary storage means respectively MZ-2and M2-1, with the parts at least of the respective codes of the primary1 and secondary 2 cells of the second representation SR2 received instep c).

a step e) in which the secondary cell 2 transmits at least onecomplementary response ERC depending on the comparison effected in stepd) and on the command contained in the complementary interrogation EIC.

Steps b) to e) can be broken down as follows:

Step b):

Two types of commands may give rise to the interrogation of primary 1and secondary 2 cells housed in a vehicle V: a command external to theinterrogator unit OI, or an automatic procedure triggered by detectingthe transit of said vehicle V.

Once warned, the control module MCOI of said interrogator unit OI thenorders the transmitter part OIE1 of the first transmission/receptionmodule to transmit a primary interrogation EIB1, EIA1 toward the primarycell 1. This primary interrogation EIB1, EIA1 consists of a for exampleamplitude-modulated (AM) carrier at 2280 Hz. However, phase-modulationor any other manner of modulation may also be employed.

The primary interrogation is carried out in two sub-steps. In a firststep, a so-called "basic" primary interrogation EIB1 is transmitted soas to request the primary cell to return a part at least of the firstcode which it contains in its primary memory M1. If the strength of thesignal is sufficient, and if the primary cell recognizes the carrierwithin a given time span, then the primary control module MC1 passesfrom the standby state to the operating state, this implementing atimeout circuit. The primary cell then has a first predeterminedduration in which to respond.

Said primary control module MC1 extracts a part at least of the firstcode C1 contained in the primary memory M1, and then inserts these bitsof the first code into a bit sequence. This sequence is forwarded to thetransmitter part E1 of the reception/transmission module which forwardsit using waves in the form of a basic primary response ERB1 to theinterrogator unit OI. The latter receives ERB1, effects a predeterminedprocessing of the bits of the sequence received and then effects aconfirmation primary interrogation ERAL by returning the bits thusprocessed to the first cell in a new bit sequence.

The primary cell 1 receives this bit sequence at the level of itsreception module R1, and compares it with a code stored in the primarymemory M1. If the comparison is successful, said module MC1 thenextracts the code C1 contained in the primary memory M1 and communicatesit to the transmitter part E1 of its reception/transmission module sothat the former forwards it using waves in the form of a confirmationprimary response ERA1 to the interrogator unit OI. The latter receivesERAL and stores in its memory OIM1 the representation C'1 of the firstcode C1 which it has just received.

This primary interrogation with two sub-steps makes it possible to limitappreciably the attempts at electronic fraud on the primary cell.

When the duration of the timeout has elapsed, the primary control moduleMC1 switches from the operating state to the standby state.

If the strength of the signal of the carrier is not sufficient, and/orif the primary cell 1 does not recognize the carrier, and/or if theprimary response ERB1 and/or ERAL is incomplete, the interrogator unitOI stores a first specific code CS1 in its memory OIM1.

The control module MCOI then orders the transmitter part OIE2 of thesecond transmission/reception module to transmit a secondaryinterrogation EIB2 toward the secondary cell 2. This secondaryinterrogation EIB2 is of the same type as that effected in respect ofthe basic primary interrogation of the primary cell 1. Similarly, if thestrength of the signal of the carrier is sufficient and if the secondarycontrol module MC2 recognizes the carrier within a given time span, thensaid secondary control module MC2 passes from the standby state to theoperating state, this implementing a timeout circuit. The secondary cell2 then has a second predetermined duration in which to respond.

Said secondary control module MC2 then instructs the processing moduleMT2 to extract the second code C2 contained in the secondary memoryM2-2. Said processing module MT2 then inserts the 16 bits of the secondcode C2 into a first bit sequence, at a first predetermined locationwhich will serve subsequently. This first sequence is forwarded to thetransmitter part E2 of the reception/transmission module which forwardsit using waves in the form of a secondary response ERB2 to theinterrogator unit OI. The latter receives ERB2 and stores the first bitsequence which it contains in its memory OIM2, this bringing step b) toan end.

To effect this secondary interrogation, the interrogator unit OI alsocontains a timeout of specified duration. Thus, in the event of theexceeding of said duration, or of non-complying secondary response ERB2,said interrogator unit OI triggers an alarm.

Conversely, if the primary and secondary interrogations are effectedwithin the allotted time span, the procedure continues normally withstep c).

Step c):

The control module MCOI instructs the processing module MTOI to extractthe second code C2 of 16 bits of the first bit sequence, which iscontained in the memory OIM2. The bits of this code are then permutedand then 8 bits C'2 for example are extracted from the 16 bits thuspermuted, according to a predetermined protocol.

These 8 bits C'2 are then inserted at a second location predetermined bythe first location of the first sequence, accompanied by the firstrepresentation FR1 of the first code C1 stored in the memory OIM1, intoa second bit sequence which moreover contains a command areacorresponding to a given transaction. The 8 bits C'2 and the firstrepresentation of the first code then form a second representation SR2of the first and second codes.

The second sequence is then forwarded to the transmitter part OIE2 ofthe second transmission/reception module which forwards it using wavesin the form of a complementary interrogation EIC. This terminates stepc).

Step d):

On reception of EIC, the secondary control module MC of the secondarycell 2 forwards the second bit sequence to the processing module MT2which, depending on a predetermined processing of the 8 bits C' and ontheir placement within the second sequence, generates a third C"2, whichit compares with the second C2 stored in the secondary memory M2-2.Next, said processing module MT2 compares the second representation C'1of the first code with the representation of this first code, whichlatter is stored in the secondary memory M2-1. This terminates step d).

Step e);

If the two comparisons are successful, the processing module MT2 caneffect the transaction which is contained in the command area of thesecond sequence.

To do this, said module generates a third bit sequence which it forwardsto the transmitter part E2 of the reception/transmission module whichforwards it using waves in the form of a complementary response ERC tothe interrogator unit OI. After this transmission, if the secondpredetermined duration has elapsed, the secondary control module MC2switches from the operating state to the standby state.

On reception of the complementary response ERC, the control module ofthe interrogator unit OI can either display the response to thetransaction on a screen, or communicate said response to a centralstation. This brings the procedure to an end.

Conversely, if the second response received does not comply, or if itcontains a specific code CS1 indicating that a primary or secondaryinterrogation has not succeeded, then step e) is modified as indicatedbelow.

The processing module MT2 of the secondary cell 2 increments anincrementation counter CI which it contains and which is set to zeroafter each successful transaction.

If the value of the counter CI is less than a chosen number N, forexample 3, then said processing module MT2 forwards a command code tothe transmitter part E2 of the reception/transmission module, which itthen forwards using waves in the form of a command complementaryresponse ECO to the interrogator unit OI. This command code orders thecommand module OIMC to recommence completely the procedure at step b).

The new procedure will be able to be performed at other frequencies thanthe procedure which has just run. This extra protection makes itpossible to strengthen further the protection against attempts atelectronic jamming.

As soon as the value of the incrementation counter is greater than orequal to N, the processing module MT2 of the secondary cell 2 forwardsan alarm code to the transmitter part E2 of the reception/transmissionmodule, which it forwards using waves in the form of an alarmcomplementary response ERCA to the interrogator unit OI which goesautomatically into an alarm state. Such an alarm can be displayed eitheron the screen of the interrogator unit OI or be forwarded to a centralstation.

At the same time, the control module MC2 of the secondary cell 2switches from the operating state to the standby state so as to avoidprofitless consumption of the battery which it contains in the event ofmalfunctioning of one of the elements making up the device.

Of course, in the event of the transmission of an alarm code ERCA, it ispossible to envisage the control module MC2 not switching immediatelyafter transmission, but continuing to transmit its alarm code for apredetermined duration.

Similarly, on reception of an alarm code, it is possible to envisage,for security reasons, a new interrogation of one at least of the cellsso as to avoid triggering the alarm in the event of the momentarymalfunctioning of one of the constituent elements of the device, or ofpoor reception of an interrogation by one of the cells 1 or 2, or of aresponse by the interrogator unit OI.

In this event, the alarm would be triggered only after confirmation bythe secondary cell of its alarm code.

The interrogator unit OI may either be fixed or portable. Thus, it ispossible to envisage providing the forces of law and order with portableinterrogator units, which would allow them to interrogate a suspectvehicle at any time, on command or simply on presumption. A fixedinterrogator unit could be installed at a great number of vehicletransit locations, such as for example motorways, car parks, customsposts.

Such a fixed interrogator unit can readily be made since it can bedivided into several elements as illustrated in FIG. 4, where saidinterrogator unit comprises a package B housing the processing andcontrol modules, and the memories, and is connected to twotransmission/reception modules OIE1-OIR1 and OIE2-OIR2 installed under amotor vehicle transitway.

This type of fixed device requires relatively low transmission powers,unlike a portable interrogator unit, since the possibility of spacingapart the transmission/reception modules makes it possible appreciablyto restrict the range of their field of action.

In a configuration or sic! the interrogator units are all fixed, it isquite obvious that in the event of an unsuccessful procedure upon afirst interrogation by an interrogator unit, the second verificationinterrogation will be effected by the following interrogator unit, whichwill be warned by the alarm code transmitted by the secondary cellcontinuously or repetitively.

The memories M1 and M2 of the device according to the invention beingrewritable, the codes which they contain can therefore be modified atany time, and according to a given protocol, by an interrogator unit OI.This makes it possible effectively to combat attempted thefts of filesof codes.

Moreover, the fast rate of the interrogations/responses allows thedevice to interrogate objects moving at speeds of perhaps up to around250 km/h.

However, whereas such a device is particularly apt for the control ofmoving objects, it can perfectly well be used on fixed objects.

The present invention shall not be limited to the frequencies describedabove. All other permitted frequencies may be envisaged on conditionthat they permit sufficient data flow rates between the installed cellsand the interrogator unit.

Similarly, the duration of the timeouts being remotely modifiable, it ispossible to envisage effecting the interrogation of an object of themotor vehicle type in several steps, one among them being carried out bya first interrogator unit at a first location when the object is inmotion, the other being carried out by a second interrogator unit at asecond location different from the first, when the object is stationary.

Moreover, in certain applications, as for example car park or motorwaytolls, provision may be made to equip the interrogator unit with a metaldetector suitable for informing it that it should trigger theinterrogation procedure automatically.

Finally, units of the infrared and/or seismic sensor type may beprovided in the primary cell, so as to deliver information on the stateof operation of the object in or on which the cells are housed.

I claim:
 1. Device for the telecontrol of an object (V), of the typecomprising an interrogator unit (OI) capable of effecting a primaryinterrogation using waves (EIB1, EIA1) so as selectively to interrogateat least one primary receiver/transmitter cell (1) housed in or on saidobject (V) and containing in primary storage means (M1) a first code(C1), and of receiving using waves from said primary cell (1) a primaryresponse (ERB1, ERA1) able to represent a part at least of this firstcode,characterized in that it furthermore comprises at least onesecondary receiver/transmitter cell (2) housed in or on said object (V)and containing in secondary storage means (M2) a second code (C2) and afirst representation (FR1) of a part at least of the first code (C1),and capable of transmitting, in response to a secondary interrogation(EIB2), a secondary response (ERB2) able to represent a part at least ofthis second code (C2), as well as of transmitting, after a primaryinterrogation of the primary cell (EIB1, EIA1) and a secondaryinterrogation of the secondary cell (EIB2), at least one complementaryresponse (ERC) in response to a complementary interrogation (EIC)effected by the interrogator unit (OI), said complementary interrogation(EIC) containing a second representation (SR2) of a part at least of thefirst and second codes transmitted respectively by said primary (1) andsecondary (2) cells in response to the primary and secondaryinterrogations (EIB1, EIA1 and EIB2), this allowing the secondary cell(2) to effect a complementary response (ERC) depending on the primaryand secondary responses of the primary (1) and secondary (2) cells,respectively.
 2. Device according to claim 1, characterized in that thetransmission/reception links between the interrogator unit (OI) and theprimary (1) and interrogator unit (OI) and the primary (1) and secondary(2) cells are effected on frequencies which are at least in partdistinct.
 3. Device according to claim 2, characterized in that thetransmission/reception links are effected on at least four distinctfrequencies, this allowing the interrogator unit (OI) to storeselectively the part at least of the first and second codes transmittedby the primary (1) and secondary (2) cells in response to the primaryand secondary interrogations (EIB1, EIA1 and EIB2), depending on thefrequency of transmission of the responses of each cell.
 4. Deviceaccording to claim 1, characterized in that the complementaryinterrogation (EIC) furthermore comprises a command area which includesa command to execute a "transaction",and in that in the event of absenceof response of one at least of the primary (1) and secondary (2) cells,the second representation (SR2) of the part at least of the absent codeis replaced with a specific code (CS1) declaring absence of said absentcell.
 5. Device according to claim 4, characterized in that thesecondary cell (2) furthermore comprises processing means (MT2) capableof comparing the codes of the primary and secondary cells, contained inits secondary storage means (M2-1 and M2-2), with the secondrepresentation (SR2) of the parts at least of the respective codes ofthe primary and secondary cells included within the complementaryinterrogation (EIC).
 6. Device according to claim 5, characterized inthat in the event of successful comparison with the codes contained insaid secondary storage means (M2), the secondary cell (2) is capable ofexecuting the transaction.
 7. Device according to claim 5, characterizedin that in the event of at least partially unsuccessful comparison, thesecondary cell (2) is capable of transmitting a command complementaryresponse (ERCO) suitable for instructing the interrogator unit (OI) torecommence at least once the primary and secondary interrogations (EIB1,EIA1 and EIB2) of the primary (1) and secondary (2) cells,and in thatthe secondary cell (2) furthermore comprises an incrementation counter(CI) which can be incremented during each partial or otherwisecomparison made.
 8. Device according to claim 7, characterized in thatthe number of permitted incrementations of the counter (CI) ispredetermined,and in that the secondary cell (2) is also capable, in theevent of the exceeding of the predetermined number, of transmitting analarm complementary response (ERCA).
 9. Device according to claim 4,characterized in that the primary (M1) and secondary (M2) storage meansare rewritable.
 10. Device according to claim 9, characterized in thatthe interrogator unit (OI) is also capable of modifying on command thefirst code (C1) contained in the primary storage means (M1) and itsfirst representation (FR1) in the secondary storage means (M2-1), and/orthe second code (C2) contained in the secondary storage means (M2-2).11. Method for the telecontrol of an object, in which:a) the object (V)is furnished with at least one primary receiver/transmitter cell (1)housed in or on said object (V) and containing in primary storage means(M1) a first code (C1), and capable of transmitting a primary response(ERB1, ERA1) in response to a primary interrogation (EIB1, EIA1), b) aprimary selective interrogation using waves of this primary cell (1) isundertaken, and a primary response (ERB1, ERA1) able to represent a partat least of the first code (C1) is received from said primary cell (1),characterized in that: in step a), there is provided at least onesecondary receiver/transmitter cell (2) housed in or on said object (V)and containing in secondary storage means (M2-1 and M2-2) a second code(C2) and a first representation (FR1) of a part at least of the firstcode (C1), said secondary cell (2) being capable of transmitting asecondary response (ERB2) in response to a secondary interrogation(EIB2) effected by an interrogator unit (OI), and at least onecomplementary response (ERC) in response to a complementaryinterrogation (EIC) effected by said interrogator unit (OI), in step b)a secondary selective interrogation using waves of the secondary cell(2) is undertaken, and a secondary response (ERB2) able to represent apart at least of the second code (C2) is received from said secondarycell (2), and in that it furthermore comprises: a step c) in which thereis transmitted to the secondary cell (2) a complementary interrogation(EIC) containing a second representation (SR2) of a part at least of thefirst and second codes transmitted by said primary and secondary cellsin step b), a step d) in which the secondary cell (2) compares thesecond code (C2) and the first representation (FR1) of the first code,which are contained in its secondary storage means (M2-2 and M2-1), withthe second representation (SR2) of the parts at least of the respectivecodes of the primary and secondary cells which are included within thecomplementary interrogation (EIC) transmitted in step c), and a step e)in which the secondary cell (2) transmits at least a complementaryresponse (ERC) as a function of the complementary interrogation (EIC)received in step c).
 12. Method according to claim 11, characterized inthat there is provided in the complementary interrogation (EIC) acommand area which includes a command to execute a "transaction",and inthat in the event of absence of response of one at least of the primary(1) and secondary (2) cells, the second representation (SR2) of the partat least of the absent code is replaced with a specific code (CS1)declaring absence of said absent cell.
 13. Method according to claim 11,characterized in that in the event of at least partially unsuccessfulcomparison in step d), there is provision to recommence at least oncesteps b) to d), and to increment an incrementation counter (CI) housedin the secondary cell (C2).
 14. Method according to claim 13,characterized in that the number of permitted repetitions of steps b) tod), in the event of at least partially unsuccessful comparison, ispredetermined,and in that in the event of the exceeding of saidpredetermined number, there is provision for the secondary cell (2) totransmit an alarm complementary response (ERCA), this making it possibleto warn an interrogator unit (OI) only in the event of confirmation ofnon-success of steps b) to d).
 15. Method according to claim 11,characterized in that in step b), the primary interrogation comprises abasic primary interrogation (EIB1) and a confirmation primaryinterrogation (EIA1), and the primary response comprises a basic primaryresponse (ERB1) of the primary cell (1) so as to respond to a basicprimary interrogation (EIB1) and a confirmation primary response (ERB1)of the primary cell (1) so as to respond to a confirmation primaryinterrogation (EIA1).
 16. Method according to claim 15, characterized inthat the basic primary response (ERB1) is able to represent a part atleast of the first code (C1) of the primary cell (1),and in that theconfirmation primary interrogation (EIA1) comprises at least one codeable to represent the part at least of the code contained in the basicprimary response (ERB1), and in that the confirmation primary response(ERA1) is able to represent a part at least of the first code (C1) ofthe primary cell (1).